Nano Research
·
2019
·Vol. 12
·期 5
·1093-1098
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IF 8.515
Huang Hong,Gong Feng,Wang Yuan,Wang Huanbo,Wu Xiufeng,Lu Wenbo,Zhao Runbo,Chen Hongyu,Shi Xifeng,Asiri Abdullah M.,Li Tingshuai,Liu Qian,Sun Xuping
Currently, industrial-scale NH 3 production almost relies on energy-intensive Haber-Bosch process from atmospheric N 2 with large amount of CO 2 emission, while low-cost and high-efficient catalysts are demanded for the N 2 reduction reaction (NRR). In this study, Mn 3 O 4 nanoparticles@reduced graphene oxide (Mn 3 O 4 @rGO) composite is reported as an efficient NRR electrocatalyst with excellent selectivity for NH 3 formation. In 0.1 M Na 2 SO 4 solution, such catalyst obtains a NH 3 yield of 17.4 μg·h −1 ·mg −1 cat . and a Faradaic efficiency of 3.52% at −0.85 V vs. reversible hydrogen electrode. Notably, it also shows high electrochemical stability during electrolysis process. Density functional theory (DFT) calculations also demonstrate that the (112) planes of Mn 3 O 4 possess superior NRR activity.
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APPLIED CATALYSIS A-GENERAL
·
2019
·
IF 4.63
Yuxing Wang,Qingji Ying,Yaoyu Zhang,Yue Liu,Zhongbiao Wu
In this paper, the reaction behaviors of CH 3 CN catalytic combustion over CuCeO x -HZSM-5 catalysts prepared by the physical mixing and wet impregnation methods were investigated. The experimental results had revealed that the composite catalysts exhibited excellent degradation efficiency and high N 2 selectivity: the Cu-Ce oxides ensured the high activity, and the introduction of HZSM-5 limited the formation of NO x . The involved reaction mechanism was then studied by an in situ DRIFT analysis. It could be deduced that different reaction pathways would occur over CuCeO x and HZSM-5. The catalytic reaction over CuCeO x mainly proceeded via an oxidation pathway. The CN group could be converted to isocyanate species [NCO(a)] which would be further oxidized to NO x . Over HZSM-5, CH 3 CN was mainly hydrolyzed into ammonia. For the CuCeO x -HZSM-5 composite catalysts, the over-oxidation of NCO(a) and NH 3 was inhibited, and an internal selective catalytic reduction (SCR) reaction could occur, thereby greatly improving the N 2 selectivity.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2018
·
IF 3.141
Daofei Lv,Renfeng Shi,Yongwei Chen,Yang Chen,Houxiao Wu,Xin Zhou,Hongxia Xi,Zhong Li,Qibin Xia
A water resistant zirconium–porphyrin metal–organic framework PCN-222 was synthesized for selectively separating CO2/CH4 and CO2/N2. Isotherms of CO2, CH4, and N2 on PCN-222 at low and high pressures were respectively measured. At 298 K, CO2 uptakes at 100 and 3000 kPa were 1.16 and 13.67 mmol/g, respectively. At 298 K and 100 kPa, CO2/CH4 (50:50, v/v) and CO2/N2 (50:50, v/v) adsorption selectivities separately reached 4.3 and 73.7. At 298 K and 3000 kPa, CO2/CH4 (50:50, v/v) and CO2/N2 (50:50, v/v) adsorption selectivities were 4.7 and 32.8, respectively. Importantly, breakthrough experiments confirmed that PCN-222 could achieve the effective separation of CO2/CH4 (both 50:50 and 10:90) and CO2/N2 (both 50:50 and 15:85) gas mixtures. The dynamic regeneration experiments showed that PCN-222 maintained its initial CO2 adsorption capacity after five cycles of CO2 adsorption–desorption. This work suggested that PCN-222 was a potential candidate for selectively separating CO2/N2 and CO2/CH4.
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Asia-Pacific Journal of Chemical Engineering
·
2012
·Vol. 8
·期 4
·567-577
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IF 0.758
Ying Gu,Xiaowei Liu,Bo Zhao,Wenqiang Liu,Minghou Xu
Nitrogen species distribution during coal pyrolysis with Ca addition in N 2 , CO 2 and Ar was studied at 1000 °C using a horizontal tube furnace. In particular, the effect of Ca on the distribution of nitrogen species in N 2 and CO 2 atmospheres, which were closer to pyrolysis processes of conversional air and oxy-fuel combustion in comparison with inert Ar environment, was investigated for the first time in this work. It was found that Ca has a great effect on nitrogen species distribution during both coal and demineralized coal pyrolysis; on the other hand, CO 2 causes the formation of NO. Demineralization increases the formation of HCN and char nitrogen, but there is little effect on NH 3 formation during pyrolysis in N 2 , in contrast to pyrolysis in Ar atmosphere, which decreases NH 3 formation. A significant reduction in char yield was found after char gasification in CO 2 at 1000 °C. With two different Ca-based additives, i.e., (CH 3 COO) 2 Ca and Ca(OH) 2 , char yield decreases with the increasing amount of Ca additives in both cases. The effect of Ca on HCN and NH 3 formation during pyrolysis depends on both the form of Ca and the amount of addition. In most cases, HCN and NH 3 formation decreases with Ca addition in Ar, but increases in N 2 . Ca addition slightly promotes HCN formation during pyrolysis in CO 2 . There is no NH 3 detected during pyrolysis in CO 2 because of the reaction of NH 3 and CO 2 in the background. In addition, NO concentration decreases sharply with increasing the amount of Ca addition in the atmosphere of CO 2 , which means that Ca has an effect not only on pyrolysis, but also on gasification of char in CO 2 . In most cases, char nitrogen increases with Ca addition in N 2 or Ar. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.
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SEPARATION AND PURIFICATION TECHNOLOGY
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2024
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IF 8.1
Zhiwei Zhao,Yuan Li,Yanjie Wang,Yating Wang,Yuhao Tang,Mengyue Lu,Xu Yang,Xiaoqing Wang,Feifei Zhang,Jinping Li,Jiangfeng Yang
The enrichment of low-concentration coal-bed methane is beneficial to solving the world’s energy concerns. However, most adsorbents used for CH 4 /N 2 separation from coal-bed methane are hydrophilic and ineffective under humid conditions. In this study, a hydrophobic nickel-based metal–organic framework (TUTQ-1Ni) was developed for efficient CH 4 /N 2 separation under humid conditions. Adsorption results show that, at 298 K and 1 bar, TUTQ-1Ni exhibits the highest CH 4 /N 2 selectivity (11.0) among the reported hydrophobic CH 4 -selective metal–organic frameworks. The results of theoretical calculations reveal that multiple O/S sites provide strong adsorption affinity for CH 4 over N 2 . Further, breakthrough experiments confirm the suitability of the material for CH 4 /N 2 separation, with the separation performance being maintained at even a high relative humidity of 100 %. The pressure swing adsorption simulation results indicate that TUTQ-1Ni is a potential candidate material for the selective capture of methane from coal-bed methane.
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EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
·
2018
·Vol. 2018
·期 8
·1047-1052
·
IF 2.507
Xiaoxia Jia,Ning Yuan,Li Wang,Jiangfeng Yang,Jinping Li
Graphical Both high selectivity and adsorption capacity in the adsorptive separation of CO 2 , CH 4 , and N 2 were achieved by means of (CH 3 ) 2 NH functionalization of the unsaturated metal sites of the MOF Ni-HKUST-1. Ni-HKUST-1, with the same topological structure as Cu-BTC (HKUST-1), was synthesized by a (CH 3 ) 2 NH-assisted method. Ni-HKUST-1 with high purity (> 90 %), yield (85 %), and BET surface area (1088 m 2 /g) was successfully synthesized for the first time by using NiCl 2 . The pure-component adsorption isotherms of CO 2 , CH 4 , and N 2 on Ni-HKUST-1 were measured by the volumetric method and the data used to estimate the separation selectivity for CO 2 /CH 4 , CH 4 /N 2 , and CO 2 /N 2 binary mixtures according to the ideal adsorbed solutions theory. At 273 K and 1 atm, the selectivities for CO 2 /CH 4 , CH 4 /N 2 , and CO 2 /N 2 were 14.49, 5.36, and 183.41, respectively, and the adsorption capacities for CO 2 and CH 4 were 223.87 and 67.89 cm 3 /g, respectively. This is a rare demonstration of both high selectivity and adsorption capacity in the separation of CO 2 , CH 4 , and N 2 .
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2018
·
IF 3.141
Yongwei Chen,Houxiao Wu,Zewei Liu,Xuejiao Sun,Qibin Xia,Zhong Li
Mechanochemical synthesis, driven the chemical transformation by mechanical force, has been a rapid and efficient strategy to prepare metal–organic frameworks (MOFs). In this work, a liquid-assisted mechanochemical method has been successfully applied to the synthesis of copper based MOF-505. The crystallinity and porosity of MOF-505 were investigated by adjusting the synthesis parameters, such as added solvent (type and amount) and grinding time. Results showed that the type and amount of added solvent were crucial parameters for the mechanochemical synthesis of MOF-505. Furthermore, the optimizations of MOF-505 synthesis were carried out: grinding Cu(OAc)2·H2O and H4bptc as starting materials for 80 min with 0.4 mL of DMF assisted, giving MOF-505-K with Brunauer–Emmett–Teller (BET) surface area of 977 m2/g. Meanwhile, MOF-505-K had moderate CO2 adsorption capacity of 2.01 mmol/g at 298 K and 100 kPa. The adsorptive selectivity determined from ideal adsorbed solution theory (IAST) indicated that MOF-505-K had high CO2/N2 and CO2/CH4 selectivities (26.6 and 5.5) at 298 K. Highly efficient mechanochemical synthesis of MOF-505 provides the promise to facilitate the industrial application of CO2 capture.
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CHEMICAL ENGINEERING JOURNAL
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2024
·
IF 13.3
Tianren Liu,Wensheng Zhang,Qingmei Tan,Weilong Lian,Haiting Lin,Jianshen Li,Dongxue Han,Yingying Fan,Dongdong Qin,Li Niu
Photocatalytic synthesis of ammonia (NH 3 ) from nitrogen (N 2 ) offers a promising strategy for carbon neutrality, as it avoids the energy-intensive and carbon-emitting industrial processes. The exploration of high-efficiency N 2 photofixation systems for photocatalytic N 2 reduction reaction (pNRR) is critical but it remains a challenge since the lack of rational structural design and atomic-level insights into molecular N 2 activation mechanism. Herein, an atomically dispersed single-atom palladium (Pd) active sites decorated oxygen-deficient molybdenum oxide (Pd/MoO 3-x ) was creatively designed for assessing pNRR performance. Interestingly, the integration of single-atom Pd active sites in MoO 3-x can significantly weaken the N≡N bond of adsorbed N 2 and effectively lower the activation energy barrier during the pNRR process. This is attributed to the fact that the modified Pd single-atom sites of Pd/MoO 3-x play a dominant role in the N 2 spontaneous adsorption process as well as possess a remarkable photogenerated electron trapping ability, which could be assisted to inject electrons into N 2 antibonding orbital, thus significantly accelerates the reaction kinetics. Consequently, the Pd/MoO 3-x photocatalyst reaches an impressive NH 3 yield rate of 103.2 μgg cat . −1 h −1 , which is superior to that of pristine MoO 3-x (21.2 μgg cat . −1 h −1 ) and commercial MoO 3 (6.5 μgg cat . −1 h −1 ), respectively. The present study not only creates a reliable approach to expand efficient N 2 photofixation system under mild conditions through the fabrication of atomically dispersed monometallic active sites, but also offers atomic-level insights into the underlying mechanism of pNRR catalytic process.
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Processes
·
2024
·Vol. 12
·期 9
·1879
·
IF 2.8
Huiying Yang,Xiangchao Meng
The conversion of nitrogen (N2) and water (H2O) into NH3by photocatalysis under ambient conditions has been considered an environmentally friendly strategy. However, developing effective catalysts for N2fixation is still challenging. Herein, we report a bimetallic JH Fe, Co/TiO2derived from NH2-MIL-125(Ti) by the fast Joule heating (FJH) method for visible–light–driven catalytic N2fixation. It was found that the photocatalytic N2reduction efficiency of bimetallic FC@TiO2-JH was improved, enabling an NH3yield rate of 110.14 µmol g−1h−1without any sacrificial agents. Furthermore, the rate was higher than those of Fe@TiO2-JH and Co@TiO2-JH, suggesting that the synergistic effect between Fe and Co broke the electronic equilibrium and increased the center of its d-band, enhancing electronic feedback to the antibonding π* orbitals of N2while weakening the bonding energy of N≡N. Meanwhile, the rate was about 2.75 times higher than that of FC@TiO2-TF, which was calcined in a tube furnace. It is assumed that FJH might lead to the formation of lattice defects, leading to localized charge deficiency, enhanced carrier separation, and transport. Thus, doping of Fe and Co synergistically interacted with the defects produced from FJH, facilitating the photocatalytic reduction process. As detected, it had a greater ability to separate hole–electron pairs and transferred electrons to adsorbed N2at faster rates. Our work demonstrates a prospective strategy for designing bimetallic catalysts derived from NH2-MIL-125(Ti) for N2fixation.
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FUEL
·
2024
·
IF 6.7
Kai Zhang,Rui Zhang,Yuxin Cui,Jiayin Shang,Xueling Wei,Sumin Wang,Siqin Jia,Ke Qin,Haiyan Zhang,Hongyan Wang,Taotao Ai,Qiguan Wang
The electrocatalytic nitrogen reduction reaction (NRR) to synthesize ammonia is an important and challenging task in chemistry, where low-cost, highly active non-metallic catalysts such as boron carbonitride (BCN) are still highly desired. Tuning the electronic environment of the active site B is an effective approach to improve the NRR performance of BCNs. However, the study on the mechanism of this effect has been seriously neglected. The diversity and controllability in atomic arrangements of BCN make it suitable for studying the relationship between the local chemical environment of boron and the catalytic properties. To this end, we design four kinds of BCN materials named as homogeneous BCN nanoribbon and BCN nanosheet enriched with B − C active sites and localized phase-separated BCN nanoribbon and BCN nanosheet rich in B − N active sites, and theoretically screen the homogeneous type BCN nanoribbons that have better NRR performances. Meanwhile, we experimentally demonstrate that the optimized charge redistribution of B atoms in BCN skeleton by tuning the electronic environment makes the B − C sites being the effective centers in NRR, and arising the excellent NH 3 productivity of 63.02 μg h −1 mg − 1 cat with a highest Faraday efficiency of 32.28 %.
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SURFACE & COATINGS TECHNOLOGY
·
2024
·
IF 5.3
Tongguo Huo,Dan Zhu,Jianxin Zheng,Yuan Lin,Yu Dai,Jian Wu
This study systematically investigated for the first time the effects of varying the temperature, pressure, C/Si molar ratio, and H 2 /Si molar ratio on β-SiC coatings produced via chemical vapor deposition (CVD) using the SiCl 4 –CH 4 –H 2 –N 2 system. Thermodynamic theoretical calculations were performed using the HSC Chemistry software. The temperature and C/Si molar ratio considerably affected the morphology, phase, and composition of β-SiC coatings. High-quality β-SiC coatings along the (111) crystal plane exhibiting a uniform surface, high density, low roughness, and good crystallinity were successfully synthesized at 1523.15 K and 200 Pa with a C/Si molar ratio of 1.0 and H 2 /Si molar ratio of 6.5. Additionally, when N 2 was used as the dilution gas instead of Ar, the resulting β-SiC coatings demonstrated reduced roughness, fewer free carbon, increased hardness (37.05 GPa vs. 39.19 GPa), enhanced modulus of elasticity (237.26 GPa vs. 264.24 GPa), and superior coating adhesion (16.48 MPa vs. 18.29 MPa).
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POLYMER
·
2025
·
IF 4.5
Shuang Wang,Dudu Li,Zelong Xu,Fan Zhou,Zhihua Qiao,Zibo Yang,Zhi Wang
Coordination polymer (CP) glasses offer high processability and permanent accessible pores, having promising potential in gas separation. However, their low porosity makes it difficult to prepare high-performance gas separation membranes. In this work, we combined the advantages of CP glasses and inorganic fillers, and selected ag Zn-P-dmbIm as the continuous phase and hydroxylated multi-walled carbon nanotubes (HMWCNTs) as the dispersed phase to prepare HMWCNTs/ ag Zn-P-dmbIm mixed matrix membranes (MMMs). The very favorable interfacial compatibility and excellent CO 2 /N 2 gas separation performance of the MMM-2 membrane were demonstrated by a series of characterizations. The test results revealed that the CO 2 permeability and ideal CO 2 /N 2 selectivity of MMM-2 membrane were 9776.8 Barrer and 31.1, respectively, which exceeded the Robeson 2019 upper bound. In addition, the well-defined long-term stability of the MMM-2 membrane lays the foundation for realizing gas separation membranes for industrial applications in practice. This provides a strategy for the subsequent preparation of CP glasses-based MMMs.
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